Enzyme-mimicking single-atom FeN4 sites for enhanced photo-Fenton-like reactions

In this study, bio-inspired single-atom Fe (bio-SA-Fe) sites with pyrrole-type FeN4 coordinations were embedded in graphitic carbon nitride (g-C3N4) via facile copolymerization approach. The bio-SA-Fe/g-C3N4 outperforms pure g-C3N4 and Fe-doped g-C3N4 (pyridine-type FeN4 sites) in photo-Fenton-like reaction with a broad operating pH range (3−9), low consumption of H2O2, and remarkable stability and durability. Bader charge and differential charge distribution reveals the pyrrole-type FeN4 sites are more conducive to charge distribution than the pyridine-type FeN4 sites in g-C3N4, enabling faster electron transfer between the conjugated bio-SA-Fe sites and the g-C3N4 substrate. Density functional theory calculations further verified that the bio-SA-Fe sites are more stable and possess higher intrinsic activity for heterogeneous Fenton reaction than the pyridine-type FeN4 sites in g-C3N4. This work provides important guidance for the rational design of robust bio-inspired single-atom catalysts for environmetal remediation and wide implications for other aqueous redox reactions.